Las referencias

“Historical Origin of the Decimal System.” UF: Department of Mechanical and Aerospace Engineering, University of Florida, www2.mae.ufl.edu/~uhk/DECIMAL-SYSTEM.pdf.

Lara-Alecio, Rafael, et al. “A Mathematics Lesson from the Mayan Civilization.” Teaching Children Mathematics, vol. 5, no. 3, Nov. 1998, pp. 154–158. EBSCOHost, JSTOR, www.jstor.org.proxy.lib.iastate.edu/stable/41197142?seq=1#page_scan_tab_contents

Lee, Cyun. “Mayan Number System Worksheet.” Ibartman.com - the pro math teacher, Ibartman, 13 Oct. 2016, lbartman.com/worksheet/mayan-number-system-worksheet.php.

McNeill, Sheila A. “The Mayan Zeros.” The Mathematics Teacher, vol. 94, no. 7, Oct. 2001, pp. 590–592. EBSCOHost, JSTOR, www.jstor.org/stable/20870802?seq=1#page_scan_tab_contents.

O'Connor, J. J., and E. F. Robertson. “Mayan Mathematics.” MacTutor History of Mathematics archive, University of St. Andrews, Scotland, Nov. 2000, Mayan_mathematics.

Reid, Nicole. “Mayan Numerals.” Nicole Reid's Blog, Nicole Reid, nicolereid.blogspot.com/

“"Shift the Place, Shift the Value" - Understanding Adjacent Places in the Base-Ten System.” CPALMS: Where Educators Go for Bright Ideas, CPALMS, www.cpalms.org/Public/PreviewResourceLesson/Preview/28707.

Swanson, Mark. “The Babylonian Number System.” UC Denver: Department of Mathematical and Statistical Sciences, University of Colorado: Denver,    www.math.ucdenver.edu/~jloats/Student%20pdfs/15_BabylonianNumbers.pdf

Webb, Richard. “Nothing.” New Scientist, vol. 212, no. 2839, 19 Nov. 2011, pp. 40–43. EBSCOHost, Academic Search Premier, eds.b.ebscohost.com.proxy.lib.iastate.edu/ehost/detail/detail?vid=7&sid=5141ad3f-f81e-4d07-a6d2-ffaf012cb833%40sessionmgr120&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#AN=67344382&db=aph.